Technical Field
The presently disclosed subject matter relates generally to plastic containers, and more particularly to hot-fillable containers having discrete surface indentations configured to prevent permanent deformation.
Description of Related Art
Throughout the process of filling a plastic container, such as conventional hot-filled bottling techniques, the container is inherently subject external forces and to positive and negative pressures within the container. These forces and pressures can result in permanent deformation of the plastic material of the container, especially shortly after hot-filling the container, when the temperature of the plastic material is close to or above the glass transition temperature of the plastic material.
Various container configurations are known to permit temporary deformation at predefined locations on the container to compensate for negative pressure generated within the container due to cooling of the hot-filled contents after capping and sealing without permanent deformation of the container. For example, U.S. Pat. Nos. 5,303,834 and 7,334,695, each of which is hereby incorporated by reference herein in its entirety, disclose containers having recessed panels defined on the sidewalls of the containers. The recessed panels are configured to temporarily flex inwardly in response to negative container pressure, thereby reducing the volume of the container and eliminate a portion of the vacuum in the container. U.S. Pat. No. 7,334,695 discloses improvements in recessed panel design which permit vacuum compensation while also preventing permanent container bulging due to positive pressure during the filling process. Additionally or alternatively, and as disclosed in, for example, U.S. Pat. Nos. 6,662,960 and 7,481,375, each of which is hereby incorporated by reference herein in its entirety, one or more reinforcing ribs or grooves, such as horizontal ribs or grooves, may be defined in the container sidewall. Such ribs and grooves provide regions of increased radial stiffness to resist deformation of the container material beyond its plastic limit when subject to internal pressures and external loads.
However, consumer demand for packaged products is heavily influenced by aesthetic considerations of the packaging itself. Container design is therefore circumscribed by a need to provide containers having certain surfaces generally unencumbered by functional geometric features. Presently available plastic containers having pleasing surface aesthetics remain susceptible to permanent deformation during hot fill processing, handling and/or conveyance. Accordingly, there remains a continued need for improved, deformation-resistant plastic containers.